Mozambique officials have confirmed the first cases of cholera in the cyclone-ravaged city of Beira.
The five cholera cases are in Munhava, one of the poorest neighbourhoods in the hard-hit port city.
Beira, which is home to around 500,000 people, is struggling to provide clean water and sanitation after Cyclone Idai ripped through Mozambique, Zimbabwe and Malawi earlier this month.
More than 1,000 people are thought to be dead in Mozambique alone after the cyclone and torrential rains. The UN estimates that more than 350,000 people are still at risk due to rising water levels in urban and rural areas.
UNICEF warned that 900,000 children have been affected by the cyclone, who are either orphaned, separated from their families or lacking basic necessities.
Cholera is a major concern for cyclone survivors who are now living in crowded camps, schools, churches and any land exposed by the draining flood waters after hundreds of thousands of homes were destroyed.
The infectious disease is spread by contaminated food and water that causes severe diarrhoea and can kill within a matter of hours.
Some people in the city have resorted to drinking water sitting on the sides of roads, which is increasing the chances of the disease, the medical charity Doctors Without Borders said.
Other people are said to be drinking from contaminated wells, with the aid group claiming they had seen hundreds of cases of acute watery diarrhoea in the past few days.
Gert Verdock of the aid group said: “The scale of extreme damage will likely lead to a dramatic increase of waterborne diseases, skin infections, respiratory tract infections and malaria in the coming days and weeks”.
The World Health Organization also warned of a “second disaster” if waterborne diseases such as cholera spread in the devastated region.
Mozambican President Filipe Nyusi is set to address the nation on Wednesday afternoon about how the government is responding to the cyclone.
Emergency responders have claimed the number of victims will likely rise as more bodies could be found as floodwaters drain away, adding that the actual number of deaths may never be known.
The UK’s total support for Cyclone Idai disaster stands at £22m, including £4m of aid match money for the Disasters Emergency Committee appeal.
The UN has also urged the international community to fund a $ 282m (£214m) emergency appeal for the next three months.